The present disclosure relates to a position control apparatus and a position control method that control a spot position of laser light radiated to an optical disc recording medium.
As optical recording media in which a signal is recorded or reproduced by radiation of light, so-called optical disc recording media (hereinafter, simply referred to as optical discs) such as a compact disc (CD), a digital versatile disc (DVD), and a Blu-ray disc (BD: registered trademark) have spread widely.
In addition, recording/reproducing apparatuses that perform recording/reproducing with respect to the optical discs have spread widely.
In a recording/reproducing apparatus with respect to the optical discs, tracking servo is applied to record information by a constant track pitch.
In general, in a recordable-type optical disc, a guide groove (for example, a wobbling groove) is formed with respect to a recording surface and information is recorded by a constant track pitch by applying the tracking servo to follow the guide groove.
Meanwhile, in recent years, an optical disc in which a guide groove is not formed with respect to a recording surface has been suggested. As a tracking servo method, so-called adjacent track servo (ATS) disclosed in Japanese Patent Application Laid-Open (JP-A) No. 2012-89198 has been suggested.
In the ATS, a beam spot Swr for recording to perform recording with respect to the recording surface and a spot Sats for adjacent track servo are formed. The beam spot Swr for the recording and the spot Sats for the adjacent track servo are formed by radiating laser light to form each spot S through a common objective lens. Under this situation, the tracking servo with respect to the objective lens is performed such that the spot Sats for the adjacent track servo follows a track before one lap where the beam spot Swr for the recording is formed. Thereby, information recording by a constant pitch is realized.